“I’m sorry to anyone in our studio audience that I’m breaking this news,” said a somber O’Brien. “This is absolutely shocking and horrifying.”

O’Brien’s sidekick Andy Richter and guest Will Arnett were on stage next to him and offered their own condolences to the Williams family.

“He was an amazingly kind of generous person,” said Richter. “And it’s got to be a terrible time for his family, and our thoughts go out to them.”

Arnett chimed in, “As funny as he was, he was truly one of the all-time greats. He was even better as a person … He was just one of the loveliest, sweetest, one of the kindest guys that I’ve ever worked with.”

“We’re thinking about Robin tonight,” O’Brien summed up before concluding the show.

Williams appeared on “The Conan O’Brien Show” several times his career — most recently in 2010.

As a father figure in "The Night Listener" in 2006

Photo: Everett Collection

Backstage before performing in Norfolk, Va., in 2009

Photo: Getty

Wrestling as the title character in "The World According to Garp" (with author John Irving in a cameo as the referee)

Photo: Everett Collection

With Raquel Welch on "Mork and Mindy"

As a Denver Broncos Pony Express cheerleader in 1979

Photo: AP

Heaven was both real and imaginary for Williams in "What Dreams May Come" in 1998.

Photo: Everett Collection

In "Toys" in 1992

Photo: Everett Collection

As "Patch Adams" in 1998

Photo: Everett Collection

In "Moscow on the Hudson" in 1984

Photo: Everett Collection

In "Jack" in 1996

Photo: Everett Collection

As "Jack" in 1996

Photo: Everett Collection

Performing at Hard Rock Live in Hollywood, Fla., in 2009

In "Cadillac Man" in 1990

Photo: Everett Collection

With John Turturro in "Being Human" in 1994

Photo: Everett Collection

"The Adventures of Baron Munchausen" in 1988

Photo: Everett Collection

In "World's Greatest Dad" in 2009

Photo: Everett Collection

As the super-strong, spinach-loving sailor "Popeye" in 1980

Photo: Everett Collection

As a Jon Stewart-type funnyman in "Man of the Year" in 2006

Photo: Ava Gerlitz/Universal

Williams was a pawn in a board game that came to life in "Jumanji" in 1996.

Photo: Everett Collection

As a shopkeeper spreading hope through his Holocaust ghetto in Poland in "Jakob the Liar" in 1999

Photo: Everett Collection

In "Insomnia" with Al Pacino in 2002

Photo: Everett Collection

In "Boulevard" in 2014

Photo: Everett Collection

In "The Big White" in 2005

Photo: Everett Collection

With director Harold Ramis on the set of "Club Paradise" in 1986

Photo: Everett Collection

In "The Fisher King" in 1991

Photo: Everett Collection

Robin Williams and Billy Crystal in "Father's Day" in 1997

Photo: Everett Collection

In "Bicentennial Man" in 1999

Photo: Everett Collection

In "The Best of Times" with Kurt Russell in 1986

Photo: Everett Collection

Performing at the Frank Erwin Center in Austin, Texas, in 2009

Photo: FilmMagic

Filming "The Angriest Man in Brooklyn" in 2012

Photo: Getty

Mork also found himself landing on "Happy Days," in two appearances in 1978 and 1979.

Photo: ABC

Opposite Al Pacino in "Insomnia" (2002)

Photo: Warner Bros.

At right in another animated persona, Fender, in "Robots" (2005)

Photo: Twentieth Century Fox

Sharing a laugh with daughter Zelda and co-star Anton Yelchin in "House of D" (2004)

Photo: Lionsgate

With Nathan Lane in the screen adaptation of "The Birdcage" (1996)

Photo: United Artists

Williams voiced this colorful penguin in "Happy Feet" (2006) and a sequel (2011).

Photo: Warner Bros.

In drag to remain with his estranged family in "Mrs. Doubtfire" (1993)

Photo: Twentieth Century Fox

Perhaps his most popular role, that of mouthy armed forces radio host Adrian Cronauer in "Good Morning, Vietnam" (1987)